1. Field of the Invention
The present invention relates to a safety needle assembly with a telescoping shield that is activated during a standard sequence of operation of a medical procedure and, more particularly, relates to a needle and hub assembly having a telescoping shield that is activated when a sampling tube is removed from a needle holder.
2. Description of the Related Art
An evacuated collection tube, needle cannula (generally a double ended needle cannula) and needle holder are commonly used by a doctor, phlebotomist or nurse to draw a sample of body fluid from a patient in a hospital or doctor's office for diagnostic testing. During the use of such a collection needle assembly, the distal end of the needle cannula in the needle holder is inserted into the vein of the patient. The evacuated collection tube is then inserted into the proximal end of the needle holder until a needle (the proximal end of a double ended needle cannula) within the needle holder pierces a closure on the end of the tube. The vacuum in the tube then draws a body fluid sample from the patient through the needle cannula and into the tube. After the collection process is complete the needle cannula is removed from the vein and disposed of.
Because of the great concern that users of such needles may be contaminated with the blood of a patient by accidental sticks from the contaminated needle, it is preferable to cover the contaminated needle as soon as it is removed from the vein. For this reason, many developments have been made to provide means for covering the contaminated needle once it is removed from the patient. These devices usually involve some sort of shield arrangement that moves in place over the contaminated needle once it has been removed from the patient. However, these shield arrangements have required the use of one or two hands to perform the operation of moving the shield over the contaminated needle, which is a hindrance to the user.
Alternatively, needles with internal or external blunting cannulas have been used that extend from the needle to blunt the distal end. However, these devices require an additional manual operation to drive the blunting cannula over or out of the needle upon completion of blood drawing to protect the user from the sharp end of the needle and also allow the user to draw blood without triggering the safety device. Such devices also require the internal diameter of the needle to be decreased, which may affect blood flow or require the external diameter of the needle to be enlarged and may cause unnecessary discomfort to the patient.
Other needles have shields that are activated during the venipuncture operation when the shield comes in contact with the skin. Using the skin to activate the device is not desirable since the device may not activate if the needle does not penetrate sufficiently or may cause the shield to inadvertently lock when probing for the vein. Such devices may also require excessive penetration into some patients to cause the triggering means to activate the device, which will cause a phlebotomist to unnecessarily have to change their standard method or procedure.
U.S. Pat. Nos. 5,718,239 and 5,893,845, which are incorporated herein by reference, provide safety needle assemblies incorporating a telescoping shield that extends over the distal end of the needle cannula when released by an actuator that is triggered during a standard sequence of operation of a medical procedure. In particular, when the closure or stopper on the collection tube compresses a rubber multiple sample sleeve on the proximal end of the needle cannula, an actuator is triggered by the closure and/or sleeve to cause the telescoping shield to extend to contact the skin of a patient. Then, when the needle end of the cannula is removed from the patient, the telescoping shield continues to extend to a fully extended and locked position over the distal end of the needle cannula, thereby rendering the needle assembly safe and preventing needle stick injuries.
Although providing significant improvements over the prior art systems, the system of the '239 and '845 patents involving deployment of the telescoping sleeve upon tube insertion can be a distraction to the user, in the event they must probe for the vein after shield is activated. There is a need, therefore, for a safety shielding needle mechanism that does not require manipulation beyond that which is familiar to medical technicians with the use of conventional blood collection needles and which is deployed following the withdrawal of the tube from the needle holder.
An object of the present invention is to provide a needle shield that is automatically activated during the normal procedure used during blood collection. It is a further object of the present invention to provide a needle assembly shielding mechanism that is activated upon insertion of an evacuated tube into the needle holder and deployed upon withdrawal of the tube from the needle holder.